Photovoltaic solar energy collection devices used to generate electric power generally include flat-panel collectors and concentrating solar collectors. Flat collectors generally include PV cell arrays and associated electronics formed on semiconductor (e.g., monocrystalline silicon or polycrystalline silicon) substrates, and the electrical energy output from flat collectors is a direct function of the area of the array, thereby requiring large, expensive semiconductor substrates. Concentrating solar collectors reduce the need for large semiconductor substrates by concentrating light beams (i.e., sun rays) using, e.g., a parabolic reflectors or lenses that focus the beams, creating a more intense beam of solar energy that is directed onto a small PV cell. Thus, concentrating solar collectors have an advantage over flat-panel collectors in that they utilize substantially smaller amounts of semiconductor. Another advantage that concentrating solar collectors have over flat-panel collectors is that they are more efficient at generating electrical energy.
A problem with conventional concentrating solar collectors is that, unlike flat-panel solar collectors, they are expensive to operate and maintain. Unlike flat-panel collectors that are laminated into a single rigid sheet, the reflectors and/or lenses used in conventional concentrating collectors to focus the light beams are produced separately, and must be painstakingly assembled to provide the proper alignment between the focused beam and the PV cell. Over time, the reflectors and/or lenses can become misaligned due to thermal cycling or vibration, thus requiring expensive maintenance to adjust the reflectors/lenses, which is not ever required with flat-panel collectors. Moreover, when the reflectors and/or lenses of conventional concentrating collectors become dirty due to exposure to the environment, maintenance in the form of cleaning and adjusting the reflectors/lenses can be significant, particularly when the reflectors/lenses are produced with uneven shapes that are difficult to clean. In contrast, flat-panel solar collectors are easy to clean due to their substantially flat surfaces. Thus, although flat-panel collectors may be more expensive to produce due to the relatively large amounts of semiconductor, concentrating solar collectors are substantially more expensive to maintain.
What is needed is a concentrator photovoltaic device that provides both the production-cost benefits of concentrating solar collectors and the maintenance-cost benefits of flat-panel solar collectors.